The tyrosine kinase receptor FLT3 expressed on the cell surface of hematopoietic progenitor cells plays an important role in early hematopoiesis. Due to its pivotal role in regulating survival, proliferation, and differentiation of hematopoietic cells (B and T cells), aberrant FLT3 activity is involved in the development and progression of cancers of the hematopoietic system. For example, internal tandem duplications of FLT3 are the most common mutations associated with acute myelogenous leukemia (AML). There is thus need in the art for antibodies that can specifically target and destroy FLT3-expressing cells.
Thus, one object of the inventors of the present invention was to provide anti-FLT3 antibodies that can bind to and kill FLT3-expressing cells in vivo.